Figure 2.

Identification of new connexin43 5′-UTRs in rat. (A) RT–PCR of total RNA prepared from various rat tissues including heart (H), uterus (U), ovary (O), mammary gland (MG), brain (B) and liver (Li). A common antisense primer annealing to the cx43 coding region and variable forward primers specific to each of the new exons (see Materials and Methods for sequence and details) were used. The PCR products were analyzed in a 2% agarose gel and visualized by ethidium bromide staining. Subcloning and sequencing of the bands confirmed that the products contain the cx43 UTR1A, 1A_L, 1A_S, 1B, 1C_L and 1C_S sequences, as indicated on the right-hand side of the panels. n.s. indicates a non-specific PCR product. On the left-hand side, the position of the molecular weight markers (PCR markers; Promega) is indicated. (B) Diagram showing the structure of the transcripts originated from the rat cx43 gene. (C) Diagram showing the genomic organization of the new exons and the splicing combinations found in rat cx43 mRNAs. Exons1A_S and exon1A partially overlap (11 nt).